Fringe fields are important when examining molecular orientation in a cold ammonia beam
Fringe fields are important when examining molecular orientation in a cold ammonia beam
复制标题
在检查冷氨束中的分子取向时，边缘场非常重要
DOI：
10.1088/1361-6455/ac34dc
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Bertier P
中科院分区：
文献类型：
--
作者：
Bertier P
外场被广泛用于控制和操纵气相分子物种的性质。特别是，电场已经被证明可以聚焦、过滤和减速极性分子的光束。虽然有几种成熟的方法来控制反应物分子的速度和量子态分布，但这些方法中很少有方法检查得到的光束中分子的取向。在这里，我们展示了缓冲气体室和三弯静电导向器(耦合到飞行时间设置)可以被配置成使得冷分子束中70%的氨分子在检测点被定向到外部电场。对装置稍作改动，就可以看到分子取向的近似统计分布。对分离四极导轨和排斥板的网格附近的电场的模拟解释了这些观测结果。因此，组合的实验装置提供了对分子束的三个关键性质的控制：旋转态分布、束流速度和分子取向。对分子束的性质施加这种级别的控制，为我们了解每个参数在反应研究中所起的作用开辟了令人兴奋的前景。
External fields have been widely adopted to control and manipulate the properties of gas-phase molecular species. In particular, electric fields have been shown to focus, filter and decelerate beams of polar molecules. While there are several well-established approaches for controlling the velocity and quantum-state distribution of reactant molecules, very few of these methods have examined the orientation of molecules in the resulting beam. Here we show that a buffer gas cell and three-bend electrostatic guide (coupled to a time-of-flight set-up) can be configured such that 70% of ammonia molecules in the cold molecular beam are oriented to an external electric field at the point of detection. With a minor alteration to the set-up, an approximately statistical distribution of molecular orientation is seen. These observations are explained by simulations of the electric field in the vicinity of the mesh separating the quadrupole guide and the repeller plate. The combined experimental apparatus therefore offers control over three key properties of a molecular beam: the rotational state distribution, the beam velocity, and the molecular orientation. Exerting this level of control over the properties of a molecular beam opens up exciting prospects for our ability to understand what role each parameter plays in reaction studies.